This invention relates to methods and apparatus for erecting a carton from a flat carton blank. Primarily, the invention relates to the erection of cartons which are comprised of a bottom part in the form of a tray and a lid part in the form of a further tray which is hingedly connected to the bottom part and fits outside its side walls when closing the carton. More particularly, the invention relates to the erection of such bottom trays and lid trays which at two opposite side panels are provided with edge flaps which are to be folded down against the interior surfaces of the side panels and are secured thereto by means of gluing.
It is previously known to erect the carton blanks under consideration by pressing them down into two adjacent shafts by means of a plunger. At the upper ends of the shafts are provided means for folding the side panels of the trays to their erected position and which folds the corner portions between the ends of the side panels. In a certain position within the shafts the carton has been erected and its various portions have been secured to one another by means of glue or other bonding means. The bonding means may be comprised of a heat sealable layer on the blank or it may consist of glud lines or "beads" which are applied to the blank just before it is pressed down into the shafts. When in the shaft the carton in its erected position will be subjected to the action of pressure members which during a predetermined interval act upon these parts of the carton which are to be connected with one another through gluing. According to the known methods and machines the carton will thereafter be subjected to a continued displacement downwardly to the open bottom end of the shaft where the carton is delivered to a conveyor device.
In the known machines the carton is merely guided by the plunger and the walls of the shaft. This means that the bottom of the carton will be free to move when the pressure members act on the carton by engaging the portions of the carton to be glued. However, in practice it has been found that the various portions of the carton become displaced relative to one another in an undesirable manner so that these portions in the ready-made carton will not be located in their correct positions in relation to one another. This displacement of the carton portions in relation to one another is obtained due to the fact that the portions of the carton to be secured to each other will not be kept securely in their proper positions when they are acted on by means of the pressure members at the places to be glued.